Survey of motor vehicle noise.

Transportation noise, and motor‐vehicle noise in particular, account for the steady or slowly varying ambient noise level, particularly in urban areas. Being so numerous, motor vehicles can be treated statistically, and this establishes consistent noise emission characteristics. Vehicles are categorized as: passenger cars [including light delivery trucks up to 6000 lb gross vehicle weight (GVW)], light, medium, and heavy trucks with GVW ranges of 6000–15 000, 15 000–30 000, and over 30 000 lb, respectively, tractor trailers, buses, cement‐mixer trucks, and motorcycles. Speed ranges are 20–29, 30–39, 40–49, 50–59, and 60–69 mph. The sound level of the average vehicle of a given category increases consistently with speed and weight. The average vehicle is defined as the hypothetical vehicle having a sound level (A, B, or C weighting) and band‐pressure levels equal to the weighted‐mean decibels in the statistical distributions. The rate of increase with speed is such that in going from 30–39 mph to 60–69 mph...